1. Field of the Invention
The present invention generally relates to a liquid material vaporization apparatus for a semiconductor processing apparatus, particularly to a liquid material vaporization apparatus comprising a vaporization tank provided upstream of a semiconductor processing apparatus to supply a vaporized material thereto.
2. Description of the Related Art
A liquid material vaporizer is provided with a vaporization tank which has a small capacity so that its footprint can be small. If a liquid material which has passed through a room temperature environment is charged into the small vaporization tank, the temperature of the liquid material stored in the vaporization tank suddenly decreases, thereby rendering gas flow unstable. In order to stabilize gas flow, the capacity of the vaporization tank needs to be larger, or vaporization needs to be held off until the temperature of the liquid material stored in the tank becomes high. Alternatively, the liquid material needs to be sufficiently heated before charging the liquid material into the vaporization apparatus as shown in FIG. 1.
In FIG. 1, a liquid material at room temperature is fist passed through a preheating section 13 provided with a heater 9, which is disposed upstream of a liquid material vaporization apparatus 10, so as to increase the temperature of the liquid material before being charged into the liquid material vaporization apparatus 10. The flow of the liquid material supplied to a vaporization tank 11 is controlled by a valve 6. The liquid material which has been heated is supplied near a bottom of the tank 11 via a liquid material flow line 5. The tank is provided with a heater 3 to heat the liquid material 2 inside the tank 11. The tank is a gas-tight container and the heated liquid material is vaporized inside the tank. The vaporized material is temporarily held in a vaporization compartment 12 and is discharged therefrom to a reactor via a gas flow line 4 which is provided with a valve 7 and a mass flow controller 8. The vaporization tank 11, the heater 3, the liquid material flow line 5 provided with the valve 6, and the gas flow line provided with the valve 7 and the mass flow controller 8 are enclosed in a housing 1 in order to facilitate temperature control of the above elements without influence from outside temperature changes.
In the above, if the liquid material is insufficiently heated upstream of the vaporization apparatus 1, the temperature of the liquid material in the tank fluctuates, thereby rendering the flow of vaporized material (gas flow) unstable. In order to stabilize gas flow, it may be required to wait until the temperature of the liquid material in the tank reaches a certain point. Further, the preheating section 13 uses a significant space, preventing minimization of the footprint of the vaporization apparatus. Furthermore, the preheating section including the heater is additional equipment and requires additional control.